This invention relates to compositions of matter capable of rapidly reducing the free metal ion content of an aqueous solution. More particularly, it relates to a detergent composition capable of rapidly reducing the free metal ion content of an aqueous wash solution.
Compositions of matter intended for use in softening water have been known previously. Generally these compositions contain a material which reacts with free metal ions, e.g., calcium, magnesium, iron, and aluminum found in water to form a water-insoluble precipitate. The formation of this precipitate results in a "softened water," i.e. water that contains relatively little free metal ions. These known compositions of matter are very effective in softening water in a relatively short period of time. However, there is a need in certain applications for an even more rapid removal of the free metal ions.
In particular, it is known that many, though not all, detergent compositions containing a water-soluble detergent perform best when used in an aqueous wash solution containing substantially no free polyvalent metal ions. This is because when many water-soluble synthetic detergents come in contact with free metal ions in the wash solution, there is formed a reaction product. The formation of this reaction product results in a poorer performing detergent composition, i.e. part of the organic detergent is "tied up" thereby leaving less detergent to perform its cleaning functions.
Another effect caused by free metal ions in an aqueous wash solution intended for the washing of soiled fabrics is that there is an interaction between the soil from the fabric and the free polyvalent metal ions. This interaction reduces the efficiency of the organic detergent by making the soils on the fabrics more difficult to remove.
Because of the aforediscussed reasons, many detergent compositions containing a water-soluble organic detergent intended for use in washing soiled fabrics in ordinary tap water (typically containing from 5 grains to 9 grains per gallon of free metal ions) have included therewith a builder material capable of "tying up" or sequestering the free metal ions. This "tying up" allows the organic detergent to perform its cleaning function unhindered by the free metal ions. Additionally, the tie up of free metal ions prevents a soil and free metal ion interaction to occur. Some builders form a soluble complex with the free metal ions. Other builders, e.g. the water-soluble salts of carbonates, are of the precipitating type. Unfortunately, some of the builders used in detergent compositions do not reduce the free metal ion content fast enough. That is, the builder competes with the organic detergent and the soil for the free metal ions. The result is that while some of the free metal ions are tied up or sequestered by the sequestrant, some do react with the organic detergent and the soil. To the extent that the latter two conditions occur, the cleaning performance of the organic detergent is decreased.
Accordingly, there is a need for a composition of matter to rapidly reduce the free metal ion concentration of an aqueous solution.
It is, therefore, an object of this invention to provide a composition of matter capable of rapidly reducing the free metal ion content of a solution.
It is another object of this invention to provide a composition of matter capable of rapidly reducing the free metal ion content of an aqueous solution.
A still further object of this invention is to provide a detergent composition that is capable of rapidly reducing the free metal ion content of an aqueous solution.
Another object of this invention is to provide a detergent composition that reduces the free metal ion content by providing growth sites for the rapid growth of water-insoluble salts of the said free metal ions.
These and other objects will become apparent from the description to follow.
As used herein throughout, all percentages are by weight unless otherwise stated.